Grinding or abrasive machine of the disk type



Oct. 24, 1950 F. w. BORGERSON 2,525,928

GRINDING 0R ABRASIVE MACHINE OF THE DISK TYPE Filed Nov. 18, 1948 7/5 n if 7 7 XE V 7 x 6 j INVENTOR.

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In the embodiment of my invention illustrated in the accompanying drawing, the spindle] "is Patented Oct. 24, 1950 r 1- GRINDING on ABRASIV-EM CHI E OF THE DISK TYPE'I I Fredrick Borgerson, Toledo, Ohio Application November 18, 1948, Serial No. 60,813

i This invention relates to improvements in grinding or abrasive machines of the disk type for finishing surfaces of substantial area.

The main objects of this invention are: First, to provide a grinding machine in which v the abrasive disk is so supported as to minimize the likelihood of gouging or overgrinding and at the same time is highly efficient.

Second, to provide a machine or device of this character in which substantially the whole surface of the abrasive disk may be utilized as dis- 'tinguished from rather limited areas thereof.

Third, to provide a machine or device of this character in which the holder may be rocked'and translated across the work and manipulated to bring the abrasive disk into contact with relatively narrow recessed or retracted portions f'of the work.

Fourth, to provide a holder for abrasive disks which supports the disks so that there is little likelihood of the work being injured even when the device is manipulated by comparatively un skilled workmen.

Objects relating to details and economies of the invention will appear from the description 'to follow. The invention is defined and pointed out in the claims.

A preferred embodiment of the invention "is illustrated in the accompanying drawing, in which: v

Fig. 1 is a sectional view through a grinding machine or device embodying my invention, the disk being shown in normal inflexed position.

Fig. 2 is an exploded view of the parts further illustrating their relation and structure. 5

Fig. 3 is an enlarged fragmentary view of the cushioning pad, the waterproof coating therefor being conventionally illustrated. I,

Fig. 4 is a fragmentary view illustrating one position of'the device in relation to a piece of work in which the edge of the abrasivedisk is deflected over the edge of its supporting an backing plate.

Fig. 5 is a fragmentary sectional view illustrating the abrasive pad in anotherposition relative to a piece of work against which it is pressed.

Fig. 6 is a cross sectional view on a line correof the type adapted to be movably supportedand -manually manipulated to various positions, the

hand holds and driving means not being illustrated as they will be understood by those skilled in the art to which this invention relates. The

8 Claims. (of. 51-197) 2 spindle is provided with a stud 2 threaded at its outer end to receive the nut 3 for securing the several parts to the spindle.

The spindle is shouldered at 4 at the base of "the stud to form an abutment for the hub 5 having a radial flange 6. Thebacking or supporting plate 'I'is circular and is secured to the hub 6 by means of rivets 8. The peripheral edge of the plate 1 is forwardly beveled at 9. This plate is substantially non-yielding when subject to the operating stresses or pressures under which the device is designed to be used. The pad ID has a flat rear face I I which is in supported engageme'nt throughoutwith'the backing plate.

"the choice of the operator. "disks'of this character are commercially avail- The front face [2 'of the pad I!) is spherically or convexedly curved and tapers radially tov a thin, preferably feather edge [3 which lies within but closely adjacent to the beveled edge of the supporting plate. The abrasive disk [4 is bendable and substantially resilient. Theabrasive material may beemery or sand or carborundum, depending on the requirements of thework and Suitable abrasive able; The backing plate is provided with a central nut receiving hole l5, While the pad is provided with a hole I6 registering therewith, the disk being provided with a hole I! adapted to receive the nut 3. The nut is flanged so that it overlaps the abrasive disk deflecting and clamping it upon the pad when the nut is threaded into abutting relation to the hub. The nut-is of such length that its outer end 'is in countersunk relati'onto the plane of the disk when the disk is in the flat "and is" guarded by the surrounding portions of the disk so that it does not come intdcontact with the work as the grinder is manipulated across the surface. This'permits the device being rocked from edge to edge across its axis and f'tiltedtopresent the abrasive to the work ina wide variety of positions. The disk 14 is of a diameter substantially exceeding the diameter of thebacking or supporting plate I so that it may be deflected'across the edge of the pad and the edge of the backing plate as is indicated in Fig. l. The pad Ii) is preferably formed'of felt of sub- Istahtial density but which, at the same time, is somewhat yielding and resilient. The pad, when formed of felt, is desirablyprovided with a water} proof coating conventionally shown at l8. This yields under pressure as is illustrated in Figs. 5 and 6 so that a substantial area of contact is had between the abrasive disk and the surface of the work. This greatly adds to the efliciency of the machine as compared to one in which substantially only line contact is had. At the same time undue pressure serves to produce a still wider contact, thereby largely eliminating gouging. The supporting of the disk so that its edge may be deflected over the edges of the pad and backing plate enables grinding of recessed portions of g the work and it also assists with the blending of the ground or abraded surfaces with adjacent surfaces, for example such as in repair work on fenders, automobile bodies, and the like.

The utilization of practically the entire surface of the disk greatly adds to the ilfe thereof or the amount of work which may be processed thereby. Further, the grinding disk is so sup ported that the tendency to displace the abrasive material is minimized.

I have illustrated and described my invention in an embodiment which I have found to be highly practical. I have not attempted to illustrate and describe various adaptations which I contemplate and to point out various uses and manipulations as it is believed that this disclosure will enable those skilled in the art to embody 'or adapt my invention as may be desired.

Having thus described my invention, what I claim as new and desire to secure by letters Patent is:

1 l. The combination with asubstantially resilient bendable abrasive disk; of a holder therefor comprising a spindle having a threaded stud at its outer end and a shoulder at the base of the stud, a flanged hub seating on said shoulder, a pad supporting plate secured-to the flange of the hub and having a circular forwardly beveled peripheral adge, a resiliently yieldable cushioning pad of felt having a flat rear face supported throughout by said plate and a convexedly curved front face tapering radially to substantially a feather edge which lies within but closely adjacent to the beveled edge of the supporting plate, said pad having a flexible waterproof coating, said supporting plate being, substantially non-yielding when subjected to operating pressures, said abrasive disk being arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, said supporting plate, pad, and abrasive disk having central registering holes therein, and a flared nut arranged through said abrasive disk and pad and threaded upon said spindle stud to abut said hub with its outwardly flared portion in clamping retaining engagement with the abrasive disk clamping it upon the central portion of said pad with the clamped portion deflected within the plane of the abrasive disk when-it is in normal flat extended position, the diameter of the abrasive disk exceeding that of thesupporting plate so that the peripheral portion of the abrasive disk extends radially beyond the periphery of the supporting plate and is deflectable across the peripheral edges of the pad and. the supporting plate.

2. The combination with a substantially resilient bendable abrasive disk, of a holder therefor comprising a circular pad. supporting plate adapted to be mounted upon the end of a driving spindle and having a forwardly beveled peripheral edge, a resiliently yieldable cushioning pad of felt having a flat rear face supported by said plate. throughout and having aconvex'edlycurved front face tapering radially to a thin edge which lies within but closely adjacent to the beveled edge of the supporting plate, said supporting plate being substantially non-yielding when subjected to operating stresses, said abrasive disk being arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and a spindle engaging clamping member in clamping retaining engagement with the abrasive disk clamping it upon the central portion of said pad with the clamped portion deflected within the plane of the abrasive disk when it is in normal flat extended position, the diameter of the abrasive disk exceeding that of the supporting plate so that the peripheral portion of the abrasive disk extends radially beyond the periphery of the supporting plate and is deflectable across the peripheral edges of the pad and the supporting plate.

3. The combination with a substantially resilient bendable abrasive disk, of a holder therefor comprising a circular pad supporting plate adapted to be mounted upon the end of a driving spindle, e, resiliently yieldable. cushioning pad supported by said plate throughout and having a 'convexedly curved front face which lies within but adjacent to the edge of the supporting plate, said supporting plate being substantially nonyielding when subjected to operating stresses, said abrasive disk being arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and a spindle engaging clamping member in clamping, retaining engagement with the abrasive disk clamping it upon the central portion of said pad with the clamped portion deflected within the plane of the abrasive disk when it is in normal flat extended position, the diameter of the abrasive disk exceeding that of the supporting plate so that the peripheral portion of the abrasive disk extends radiall beyond the periphery of. the supporting plate and is deflectable across the peripheral edges of the pad and the supporting plate.

4. The combination with a substantially-resilient bendable abrasive disk, of a holder therefor comprising a circular pad supporting plate adapted to be mounted upon the end of a driving spindle, .a resiliently yieldable cushioning pad supported by said plate throughout and having a convexedly curved front face which lies within but adjacent to the edge of the supporting plate, said supporting plate being substantially non-yielding when subjected 'to operating stresses, said abrasive disk being arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and a spindle engaging clamping member inclamping retaining engagement with the abrasive disk clamping. it upon the central portion of said pad.

5. combination, an abrasive disk, a spindle having a threaded stud at its outer end and a shoulder at the base of the stud, a flanged hub seatingon said shoulder, a pad supporting plate secured. to the flange of the hub, a resiliently yieldable cushioningpad disposedon said plate and having a convexedly curved front face tapering radially to an edge which lies within but adjacenttothe edge of the supporting plate, said pad having 'aflexible waterproof coating, said. supporting plate being substantially nonyielding. when subjected to operating pressures, the abrasive disk being adapted to be arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and

a flared nut threaded upon said spindle stud in clamping, retaining engagement with the abrasive disk clamping it upon the central portion of said pad with the clamped portion deflected within the plane of the abrasive disk when it is in normal flat extended position.

6. In combination, an abrasive disk, a spindle having a threaded stud at its outer end and a shoulder at the base of the stud, a flanged hub seating on said shoulder, a pad supporting plate secured to the flange of the hub, a resiliently yieldable cushioning pad disposed on said plate and having a convexedly curved front face tapering radially to an edge which lies within but adjacent to the edge of the supporting plate, said supporting plate being substantially nonyielding when subjected to operating pressures, the abrasive disk being adapted to be arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and a flared nut threaded upon said spindle stud in clamping retaining engagement with the abrasive disk clamping it upon the central portion of said pad with the clamped portion deflected within the plane of the abrasive disk when it is in normal flat extended position.

7. In combination, an abrasive disk, a circular pad supporting plate adapted for attachment to a spindle, a resiliently yieldable cushioning pad disposed on said plate and having a convexedly curved front face tapering radially to an edge which lies adjacent to the edge of the supporting plate, said supporting plate being substantially non-yielding when subjected to operating pressures, the abrasive disk being adapted to be arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and means forsecuring the central part of the abrasive disk upon the pad for rotation with the spindle, the diameter of the abrasive disk exceeding that of the supporting plate so that a peripheral portion of the abrasive disk extends radially beyond the supporting plate and is deflectable across the peripheral edges of the pad and the supporting plate.

8. In combination, an abrasive disk, a circular pad supporting plate adapted for attachment to a spindle, a resiliently yieldable cushioning pad disposed on said plate and supported through out thereby and having a convexedly curved front face tapering radially to a thin edge which lies adjacent to the edge of the supporting plate, said supporting plate being substantially nonyielding when subjected to operating pressures, the abrasive disk being adapted to be arranged upon said pad for supported engagement therewith when subjected to deflecting stresses, and means for securing the central part of the abrasive disk upon the pad for rotation with the spindle.

FREDRICK W. BORGERSON.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 251,481 Stevens Dec. 27, 1881 1,176,001 Stewart Mar. 21, 1916 1,648,663 Stratford Nov. 8, 1927 1,693,163 Schacht Nov. 27, 1928 2,260,644 Siebert et a1. Oct. 28, 1941 FOREIGN PATENTS Number Country Date 1,887 Great Britain A, D. 1905 64,715 Denmark July 8, 1926 

